That's right, you met him

He's a hambone. They're my favorite breed too. We have a friend with two Pyrs too.
Why the surgery... well he'd been limping for awhile and our regular vet, general practioner if you will said he might have growing pains (Pano) as is common in large breed dogs or he may have OCD (Osteochondritis Dessicans) and to give him light exercise and pain relievers. So we've been treating him as if he's a glass dog instead of one who is healthy etc. Call it paranoid, but big dogs are soooo prone to ortho problems and we wanted to avoid that at all costs.
Anyways, the exercise/pain relievers which we rarely used didn't do the trick, so we got an appointment with an ortho vet. We had xrays which showed OCD and we scheduled a surgery. He wound up having had OCD but it had resolved itself. What was causing the problem was joint mice which are tiny calcified pieces of cartilage that sit in between the joints and rub and grind and cause all sorts of fun. Pain being one of them. He's walking WAY better now than he did before surgery. So we're happy. Once he's all healed up, we'll do water therapy and keep him lean and trim.
We have a pic of the joint mice too if you're not grossed out.
"You can say any fool thing to a dog, and the dog will give you this look that says, `My God, you're RIGHT! I NEVER would've thought of that!'" - Dave Barry
40 gallon tall
15 gallon refugium
2.5 gallon mantis tank